The present invention relates to a ball valve device to be interposed between a couple of metallic pipes for supplying a fluid, more particularly to a ball valve device capable of cutting off the current which flows through the couple of metallic pipes coupled with both sides of the ball valve.
Liquefied Natural Gas (LNG) is universally used as fuel for cooking, heating and so on. The LNG is generally provided from a large-scale source of supply to each of users through metallic pipes. Since such pipes are electrically conductive, pipes are corroded due to several kinds of current such as earthing current by consumer goods, leakage current, static electricity and so on. Such corrosions shortenize the life of pipe and are able to cause a big accident by the leaked LNG due to the corrosions. Accordingly, one of important things in supplying LNG is to cut off the current flowing through pipes. A conductive pipe for supplying an nonconductive fluid is always raised a problem on such an electric corrosion.
In order to cut off such current flowing through the pipe, it has been known that a flange coupling including an insulating sheet and insulating spacers is interposed between pipes only for the purpose of insulating. However, this type of conventional way has a drawback in that additional costs and efforts are required for the purpose of insulating because of interposing the flange coupling additionally, and has further disadvantage in that an enough insulating effect is not guaranteed for a long time because of deteriorating the function of the insulating element such as the insulating sheet or the insulating spacers of the flange coupling due to a twisting appearance of the pipe derived from the ground subsidence.